An alkaline secondary battery, which uses a metal compound, for example, nickel hydroxide, for a positive electrode and a hydrogen-absorbing alloy for a negative electrode, has lately been attracting attention as a high energy density battery for replacing nickel-cadmium batteries.
A hydrogen-absorbing alloy performs absorption and desorption of hydrogen as an active material when a battery charges and discharges in an electrolyte. The alloy lattice is deformed by absorption and desorption of hydrogen and alloy particles are pulverized. The pulverized alloy drops or separates from the electrode to cause a reduction in capacity. It also causes mechanical strength of the electrode and electrical conductivity to deteriorate. It is difficult to maintain battery capacity for a long term.
A hydrogen-absorbing alloy powder has been combined with a binding agent of an alkali resistant synthetic resin and a thickening agent to manufacture a hydrogen-absorbing alloy electrode as disclosed in Japanese Patent Laid-Open Publication No. 61-66366.
Styrene-butadiene copolymer which has excellent pliability and adhesive strength is proposed for use as a binding agent for an electrode in Japanese Patent Laid-Open Publication No. 2-135665. In the hydrogen-absorbing alloy electrode disclosed in this publication, the binding agent is deformed with change of volume of the hydrogen-absorbing alloy powder to prevent separation of the pulverized alloy from the electrode. However, reduction of contact between hydrogen-absorbing alloy particles and an electrolyte prevents proper electrical reactions and high rate discharge characteristics of the battery are deteriorated.